Linear alkyl geminal disulfonates as phosphate-free actives

ABSTRACT

HEAVY DUTY ETERGENT ACTAIVE MATERIALS COMPRISE ORGANIC GEMINAL DISULFONATES OF THE FORMULA   R-C(-SO3-X)2-Y   IN WHICH R IS A SUBSTANITALLY LINEAR ALKYL GROUP OF 14 TO 29 CARBON ATOMS, X IS H OR A WATER-SOLUBLE, SALT-FORMING CATION, AND Y IS H,   -CO-H,   OR -CH2-OH.

UnitcdStatcs Patent 'Ofiice 3,819,691 LINEAR ALKYL GEMINAL DISUL'FONATES AS PHOSPHATE-FREE ACTIVES Victor P. Kurkov, San Rafael, and Samuel H. Sharmau, Contra Costa, Calif., assiguors to Chevron Research Company, San Francisco, Calif. No Drawing. Filed June 3, 1971, Ser. No. 150,856 Int. Cl. C07c 143/04, 143/10 US. Cl. 260-513 R 4 Claims ABSTRACT OF THE DISCLOSURE Heavy duty detergent active materials comprise organic geminal disulfonates of the formula soax R-C-Y CaX in which R is a substantially linear alkyl group of 14 to 29 carbon atoms, X is H or a water-soluble, salt-forming cation, and Y is H,

BACKGROUND OF THE INVENTION However, the above-mentioned surface-active materials are inadequate in terms of soil removal in the absence of phosphate builders. Increasing evidence appears to indicate that phosphates contribute to the growth of algae in the nations streams and lakes. This algae growth poses a serious pollution threat to the maintenance of clear, good domestic water supplies.

Consequently, there has developed a need for detergent active materials which will function successfully in the absence of phosphate builders. Recently, certain non-phosphate building materials have been proposed as replacements for the phosphates. Thus, materials such as the polysodium salts of nitrilotriacetic acid, ethylene diamine tetraacetic acid, copolymers of ethylene and maleic acid, and similar polycarboxylic materials have been proposed as builders. These materials, however, when employed with conventional detergent actives such as LAS, have, for one reason or another, not proved to be quite as eflective as phosphates in detergent formulations. For example, some of the materials have proven to be insufficiently biodegradable to meet present and anticipated requirements.

It is therefore desirable to provide compounds which are effective as detergent active materials in the absence of phosphate builders and are sufliciently biodegradable that their use does not contribute foam to the water supply.

In addition, in the past, with heavy duty detergents, it has been thought that to achieve good soil removal it was necessary to maintain a high pH in washing solutions. This concept, which began with the strongly alkaline laundry soaps, has continued to the present day LAS- phosphate combinations which are in widespread use in 3,819,691 Patented June 25, 1974 heavy duty detergent formulations. One apparent reason for this is that the alkylbenzene sulfonate detergents are not effective in heavy duty detergent formulations in the absence of a builder. The phosphate builders, for example, must be employed at a pH greater than 9 to be effective, and even the newer builders such as sodium nitriloacetate have a pH of about 9 in solution. The advantages to be gained with heavy duty detergents which may be employed at neutral pH are many. Deleterious effects from skin contact are lessened. Enzyme-type soil looseners may be more easily combined in neutral solutions. Injury to fabrics is minimized. It is, therefore, desirable to provide detergent active materials which, in addition to the previously mentioned non-polluting characteristics, achieve their maximum detergency at or near neutral pH.

The formulation of liquid heavy duty detergent compositions achieves many desirable results. They are easy to package and measure, and their use opens the possibility of automatic dispensing in washing machines. However, in the past it has been impracticable to formulate heavy duty detergents in liquid form because of the insufiicient solubility of the inorganic ingredients (phosphate builders, etc.) required for heavy duty applications and the high cost of organic substitutes for such inorganic ingredients. It is therefore highly desirable to provide detergent active materials having good water solubility and which, because of their excellent detergency without builders, can be formulated into effective, reasonably priced, heavy duty liquid detergent formulations.

DESCRIPTION OF THE PRIOR ART The sulfonation of aldehydes with sulfur trioxide-dioxane is described by A. P. Terentyev and L. A. Yanovskaya, Sulfonation and Sulfonic Acids of Acidophobic Compounds, J. Gen. Chem., U.S.S.R., 23, 643 (1953), The barium salts of the disulfonic acids of acetaldehyde, propionaldehyde, butyraldehyde, isovaleraldehyde, heptaldehyde, octaldehyde, and decylaldehyde were prepared and identified.

The preparation and cleavage of aldehyde sulfonates to yield the sulfonate derivative and formate is described by W. E. Truce and C. C. Alfeiri in Sulfonation of Aldehydes, I. Am. Chem. Soc., 72, 2740 (1950).

No utility was ascribed for either the formyl substituted or unsubstituted disulfonates.

SUMMARY OF THE INVENTION Heavy duty detergent active materials are provided which comprise organic geminal disulfonates of the formula in which R is a substantially linear alkyl group of 14 to 29 carbon atoms, X is H or a water-soluble, salt-forming cation, and Y is H,

R is preferably a linear alkyl group of 14 to 30 carbon atoms, more preferably 15 to 23 carbon atoms, and most preferably 16 to 21 carbon atoms.

The detergent active materials of this invention are most easily prepared by the reaction of a suitable linear aldehyde (or most usually the cyclic trimer of the aldehyde) with at least two mols per carbonyl group of a complex of sulfur trioxide and dioxane or sulfur trioxide and pyridine. If desired, the compounds may be converted to the alkane disulfonates by basic hydrolysis and neutralization of the sulfonic acid groups.

During the hydrolysis step, one carbon atom is lost from the original aldehyde, thus in order to reach the preferred range of 16 to 22 carbon atoms of the detergent active alkyl disulfonates it is necessary to begin with aldehydes of 17 to 23 carbon atoms, and suitable materials include heptadecanal, octadecanal, nonadecanal, eicosanal, heneicosanal, docosanal, and tricosanal. While linear materials are preferred, the presence of random methyl groups upon the compounds is acceptable.

The reaction of the sulfur trioxide-dioxane complex with the aldehyde is effected at temperatures of from about to 100 C., preferably at temperatures of 20 to 50 C. The addition of a small amount of mineral acid ensures the depolymerization of the aldehyde trimer (in which form the aldehyde is often supplied) and speeds the reaction. Times of from about 2 to 24 hours are usually sufficient for sulfonation. At the completion of the sulfonation the mixture is preferably neutralized to a pH of about 7 with a base such as sodium carbonate. The solvent is then removed by evaporation, etc., to yield the 2,2-disulfomate of the aldehyde.

The disulfonated aldehyde may then be contacted with strong aqueous base to effect decarbonylation; a time of from about 2 to 8 hours at a temperature of from 50 to 100 C. being sufficient to remove the carbonyl groups. After the decarbonylation reaction, the pure disulfonate may be recovered by extraction with a solvent, e.g. ethanol, and removal of the solvent by evaporation.

Alternatively, the carbonyl group may be reduced by conventional methods to yield the corresponding alcohols. Reduction may be effected by reaction with formaldehyde in the presence of a strong base.

EXAMPLE 1 Preparation of Sodium l-formyl-Ll-heptadecane Disulfonate Liquid S0 7.2 grams (0.09 mole), was added dropwise into a solution of 23.6 grams (0.27 mole) of dioxane in 48 ml. of dichloroethane while maintaining the temperature at 0-5 C. Then 4 grams (0.015 mole) of octadecanal trimer dissolved in 55 ml. dichloroethane was added dropwise. Next, 3 drops of concentrated sulfuric acid was added and the resulting mixture was stirred at 0-5 C. for minutes and at 32-35" C. for 17 hours. At the end of this time the reaction mixture was poured into 600 ml. of ice water and neutralized to pH 7 with sodium carbonate. The neutralized solution was evaporated to give 19.90 grams of crude product.

EXAMPLE 2 Preparation of Sodium-1,1-heptadecane Disulfonate The crude product was dissolved in 90 ml. of water and mixed with 200 ml. of aqueous sodium hydroxide. The mixture was heated at 100 C. for 4 hours, then cooled to 25 C. and neutralized to pH 7 with sulfuric acid. The solution was then filtered and extracted with 95% ethanol. The ethanol extract was concentrated and cooled to 0 C. and a solid separated from the ethanol. The precipitate was filtered from the ethanol and washed with cold ethanol. The precipitate was dried and yielded 2.79 g. of disodium hepadecyl-1,1-disulfonate.

Analysis of the material gave the following results:

Calculated: carbon, 44.15; hydrogen, 7.41; sulfur, 13.85. Found: carbon, 44.90; hydrogen, 7.28; sulfur, 13.10.

Nuclear magnetic resonance (NMR) analysis gave results consistent with the assumed structure.

EXAMPLE 3 Preparation of Linear Alkyl 1,1-Disulfonates Following the general procedures of Examples 1 and 2, 1,1-alkane disulfonates were prepared from 14, 20 and 23 carbon linear aldehydes.

Detergency of the compounds of the present invention is measured by their ability to remove natural sebum soil from cotton cloth. By this method, small swatches of cloth, soiled by rubbing over face and neck, are washed with test solutions of detergents in a miniature laboratory washer. The quantity of soil removed by this washing procedure is determined by measuring the refiectances of the new cloth, the soiled cloth, and the washed cloth, the results being expressed as percent soil removal. Because of variations in degree and type of soiling, in water and in cloth, and other unknown variables, the absolute value of percent soil removal is not an accurate measure of detergent effectiveness and cannot be used to compare various detergents. Therefore, the art has developed the method of using relative detergency ratings for comparing detergent effectiveness.

The relative detergency ratings are obtained by comparing and correlating the percent soil removal results from solutions containing the detergents being tested with the results from two defined standard solutions. The two standard solutions are selected to represent a detergent system exhibiting relatively high detersive characteristics and a system exhibiting relatively low detersive characteristics. The systems are assigned detergency ratings of 6.3 and 2.2, respectively.

By washing portions of each soiled cloth with the standardized solutions, as well as with two test solutions, the results can be accurately correlated. The two standard solutions are identical in formulation but are employed at different hardnesses.

STANDARD SOLUTION FORMULATION Ingredient: Weight percent Linear alkylbenzene sulfonate (LAS) 25 Sodium triphosphate 40 Water 8 Sodium sulfate '19 Sodium silicate 7 Carboxymethylcellulose 1 The standard exhibiting high detersive characteristics (Control B) is prepared by dissolving the above formulation (1.0 g.) in one liter of 50 p.p.m. hard water (calculated as 73 calcium carbonate and /3 magnesium carbonate). The low detersive standard (Control A) contained the formulation 1.0 g.) dissolved in one liter of p.p.m. water (same basis).

A miniature laboratory washer is so constructed that four different solutions can be used to wash different parts of the same swatch. This arrangement ensures that all four solutions are working on identical soil (natural facial soil). Relative detergency ratings (RDRs) are calculated from soil removals (SRs) according to the equation:

RDR=2.2+4.1

Percent SR .,,,Percent SR A Percent S Conti-ol B 'Percent Control A A further refinement in the determination of relative detergency ratings was developed. In this method, instead of employing two standard formulations, one of the formulations used as one of the four test solutions had a known relative detergency rating (RDR) which had been determined by the above formula. Relative detergency ratings of the other three formulations were then determined by comparing the percent soil removal (SR) of these formulations with that of the known formulation.

Table I presents detergency data derived by the abovedescribed test on detergent formulations containing the alkane disulfonate of Example 2. The formulation contained 25 weight percent of the active. Also in the formulation were 1% carboxymethylcellulose, 7% sodium sili- 'cate, 8% water, and sufficient sodium sulfate to total 100%. For comparison purposes detergency data from linear alkylbenzene sulfonate (LAS) having from 11 to 14 carbon atom straight chain alkyl groups is provided both with and without a phosphate builder. The LAS formulation contained as the active material 25% by weight. The LAS-phosphate formulation contained 20 weight percent LAS and 40% of sodium triphosphate. These formulations were prepared in the same manner as the 1,1-alkane disulfonate formulations. The pH at which the tests were run is indicated in the table.

The effectiveness of the compositions of this invention is further demonstrated in a miniature Terg-O-Tometer test. In this test, as in the previously described test, the effectiveness of the compositions is measured by their ability to remove natural sebum soil from cotton cloth. The sebum soiled swatches were obtained as previously described. The procedure employed is so designed that two standard formulations and two test formulations can be used to wash different parts of the same soiled swatch. This arrangement again ensures that all formulations are working on identical soil. Soil removals were determined from reflectances as in the previously described test.

The relative detergency ratings in this test are obtained from the soil removals as in the previously described test. However, the two standard solutions employed are different and are assigned detergency ratings of 6 and 2, respectively, for the high and low detergency systems. v

The standard formulations employed are as follows:

Formulation for the low detersive standard (Control A) Ingredient: Weight percent Alkylbenzene sulfonate 35 Sodium triphosphate 40 Water 8.5 Sodium sulfate 8 Sodium silicate 7 Carboxymethylcellulose 0.8

Formulation for the high detersive standard (Control B) Ingredient: Weight percent Linear alkylbenzene sulfonate (LAS) 7.5 Tallow alcohol sulfate Sodium triphosphate 47.5 Water 10 Sodium sulfate 13 Sodium silicate 5 Carboxymethylcellulose 1 Relative detergency (RD) values were calculated from soil removals (SR), according to the equation:

Percent SR ,Peroent SR A Percent Control B- 7 Control A In these tests the formyl derivative prepared in Example 1 and a series of the alkane disulfonates prepared by the procedures of Examples 1-3 were formulated as in the previously described test and compared with the LAS and LAS-phosphate combinations. These data are set forth in Table II following. The pH at which the tests were run as well as the number of alkyl carbons in the disulfonates is indicated.

It may be noted that the 13 carbon disulfonate has little detergent effectiveness, while the 17, 19 and 22 carbon are effective, particularly in hard water p.p.m.). The 19 carbon (nonadecyl) compound was particularly effective, approximately equalling the conventional LAS- phosphate detergent in hard water.

It will be understood that the effective compositions of this invention include those materials which comprise a mixture of the geminal disulfonates in which the alkyl groups vary in their carbon chain length between 14 and 30. Thus, in most instances, a single molecular weight species will not be as practical commercially as the mixtures, and generally most effective compositions will comprise mixtures wherein at least 10 and preferably at least 15% by weight of at least two species of the sulfonated alkylphenols are present in which R is an alkyl radical of 14, 19, 20, 21, or 22 carbon atoms. The preferred range of carbon atoms will be from about 17 to 21 and most preferably from about 18 to 20 carbon atoms.

The disulfonates may be employed in combination with other detergent active materials. They are particularly effective with other dianionic materials, examples of which include linear alkyl and alkenyl disulfates and disulfonates. Particularly useful classes of materials for use in detergent active combinations incude the linear 2- alkenyl or linear Z-alkyl 1,4-butane diol disulfates in which the alkenyl or alkyl groups contain from 15 to 20 carbon atoms and the alkylphenol disulfonates in which the alkyl group is substantially linear of 16 to 22 carbon atoms, and not more than 25 mol percent of the compounds have the alkyl group attached on the aromatic ring para to the phenolic hydroxyl.

In employing the detergent active materials of this invention in detergent compositions, they may be formulated with additional compatible ingredients being optionally incorporated to enhance the detergent properties. Such materials may include but are not limited to anticorrosion, antiredeposition, bleaching and sequestering agents, and certain organic and inorganic alkali metal and alkaline earth metal salts such as inorganic sulfates,

silicates, carbonates, or borates. Also nonphosphate builders may be included in the composition. Examples of these builders are sodium citrate, sodium diglycolate, sodium carbonate, sodium metasilicate, the sodium salts of nitrilotriacetic acid, ethylene diamine tetraacetic acid, and ethylene maleic acid copolymers, etc. Also small 7 quantities of phosphate builders may be included although, of course, they are not necessary for eflfective detergency.

While the character of this invention has been described in detail with numerous examples, this has been done by way of illustration only and without limitation of the in vention. It will be apparent to those skilled in the art that modifications and variations of the illustrative examples may be made in the practice of the invention within the scope of the following claims.

What is claimed is:

1. A compound of the formula SIOaX 8 2. The compound of claim 1 in which R is alkyl of 16 to 23 carbon atoms and Y is H.

3. The compound of claim 1 in which X is alkali metal.

4. The compound of claim 3 in which X is sodium.

References Cited UNITED STATES PATENTS 3,714,238 1/1973 Nagayama et al. 2605l3 R 3,666,796 5/1972 Nool 260513 R 3,544,475 12/1970 Tomiyama et al. 2605l3 R OTHER REFERENCES Moilliet et al., Surface Activity, p. 361 (1961). Terentev et al., Chemical Abstracts, 48, 6958d (1954).

DANIEL D. 'HORWITZ, Primary Examiner US. Cl. X.R. 

